(function(global) {
    "use strict";

    /* Set up a RequestAnimationFrame shim so we can animate efficiently FOR
     * GREAT JUSTICE. */
    var requestInterval, cancelInterval;

    (function() {
        var raf = global.requestAnimationFrame       ||
                global.webkitRequestAnimationFrame ||
                global.mozRequestAnimationFrame    ||
                global.oRequestAnimationFrame      ||
                global.msRequestAnimationFrame     ,
            caf = global.cancelAnimationFrame        ||
                global.webkitCancelAnimationFrame  ||
                global.mozCancelAnimationFrame     ||
                global.oCancelAnimationFrame       ||
                global.msCancelAnimationFrame      ;

        if(raf && caf) {
            requestInterval = function(fn, delay) {
                var handle = {value: null};

                function loop() {
                    handle.value = raf(loop);
                    fn();
                }

                loop();
                return handle;
            };

            cancelInterval = function(handle) {
                caf(handle.value);
            };
        }

        else {
            requestInterval = setInterval;
            cancelInterval = clearInterval;
        }
    }());

    /* Catmull-rom spline stuffs. */
    /*
     function upsample(n, spline) {
     var polyline = [],
     len = spline.length,
     bx  = spline[0],
     by  = spline[1],
     cx  = spline[2],
     cy  = spline[3],
     dx  = spline[4],
     dy  = spline[5],
     i, j, ax, ay, px, qx, rx, sx, py, qy, ry, sy, t;

     for(i = 6; i !== spline.length; i += 2) {
     ax = bx;
     bx = cx;
     cx = dx;
     dx = spline[i    ];
     px = -0.5 * ax + 1.5 * bx - 1.5 * cx + 0.5 * dx;
     qx =        ax - 2.5 * bx + 2.0 * cx - 0.5 * dx;
     rx = -0.5 * ax            + 0.5 * cx           ;
     sx =                   bx                      ;

     ay = by;
     by = cy;
     cy = dy;
     dy = spline[i + 1];
     py = -0.5 * ay + 1.5 * by - 1.5 * cy + 0.5 * dy;
     qy =        ay - 2.5 * by + 2.0 * cy - 0.5 * dy;
     ry = -0.5 * ay            + 0.5 * cy           ;
     sy =                   by                      ;

     for(j = 0; j !== n; ++j) {
     t = j / n;

     polyline.push(
     ((px * t + qx) * t + rx) * t + sx,
     ((py * t + qy) * t + ry) * t + sy
     );
     }
     }

     polyline.push(
     px + qx + rx + sx,
     py + qy + ry + sy
     );

     return polyline;
     }

     function downsample(n, polyline) {
     var len = 0,
     i, dx, dy;

     for(i = 2; i !== polyline.length; i += 2) {
     dx = polyline[i    ] - polyline[i - 2];
     dy = polyline[i + 1] - polyline[i - 1];
     len += Math.sqrt(dx * dx + dy * dy);
     }

     len /= n;

     var small = [],
     target = len,
     min = 0,
     max, t;

     small.push(polyline[0], polyline[1]);

     for(i = 2; i !== polyline.length; i += 2) {
     dx = polyline[i    ] - polyline[i - 2];
     dy = polyline[i + 1] - polyline[i - 1];
     max = min + Math.sqrt(dx * dx + dy * dy);

     if(max > target) {
     t = (target - min) / (max - min);

     small.push(
     polyline[i - 2] + dx * t,
     polyline[i - 1] + dy * t
     );

     target += len;
     }

     min = max;
     }

     small.push(polyline[polyline.length - 2], polyline[polyline.length - 1]);

     return small;
     }
     */

    /* Define skycon things. */
    /* FIXME: I'm *really really* sorry that this code is so gross. Really, I am.
     * I'll try to clean it up eventually! Promise! */
    var KEYFRAME = 500,
        STROKE = 0.08,
        TWO_PI = 2.0 * Math.PI,
        TWO_OVER_SQRT_2 = 2.0 / Math.sqrt(2);

    function circle(ctx, x, y, r) {
        ctx.beginPath();
        ctx.arc(x, y, r, 0, TWO_PI, false);
        ctx.fill();
    }

    function line(ctx, ax, ay, bx, by) {
        ctx.beginPath();
        ctx.moveTo(ax, ay);
        ctx.lineTo(bx, by);
        ctx.stroke();
    }

    function puff(ctx, t, cx, cy, rx, ry, rmin, rmax) {
        var c = Math.cos(t * TWO_PI),
            s = Math.sin(t * TWO_PI);

        rmax -= rmin;

        circle(
            ctx,
            cx - s * rx,
            cy + c * ry + rmax * 0.5,
            rmin + (1 - c * 0.5) * rmax
        );
    }

    function puffs(ctx, t, cx, cy, rx, ry, rmin, rmax) {
        var i;

        for(i = 5; i--; )
            puff(ctx, t + i / 5, cx, cy, rx, ry, rmin, rmax);
    }

    function cloud(ctx, t, cx, cy, cw, s, color) {
        t /= 30000;

        var a = cw * 0.21,
            b = cw * 0.12,
            c = cw * 0.24,
            d = cw * 0.28;

        ctx.fillStyle = color;
        puffs(ctx, t, cx, cy, a, b, c, d);

        ctx.globalCompositeOperation = 'destination-out';
        puffs(ctx, t, cx, cy, a, b, c - s, d - s);
        ctx.globalCompositeOperation = 'source-over';
    }

    function sun(ctx, t, cx, cy, cw, s, color) {
        t /= 120000;

        var a = cw * 0.25 - s * 0.5,
            b = cw * 0.32 + s * 0.5,
            c = cw * 0.50 - s * 0.5,
            i, p, cos, sin;

        ctx.strokeStyle = color;
        ctx.lineWidth = s;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        ctx.beginPath();
        ctx.arc(cx, cy, a, 0, TWO_PI, false);
        ctx.stroke();

        for(i = 8; i--; ) {
            p = (t + i / 8) * TWO_PI;
            cos = Math.cos(p);
            sin = Math.sin(p);
            line(ctx, cx + cos * b, cy + sin * b, cx + cos * c, cy + sin * c);
        }
    }

    function moon(ctx, t, cx, cy, cw, s, color) {
        t /= 15000;

        var a = cw * 0.29 - s * 0.5,
            b = cw * 0.05,
            c = Math.cos(t * TWO_PI),
            p = c * TWO_PI / -16;

        ctx.strokeStyle = color;
        ctx.lineWidth = s;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        cx += c * b;

        ctx.beginPath();
        ctx.arc(cx, cy, a, p + TWO_PI / 8, p + TWO_PI * 7 / 8, false);
        ctx.arc(cx + Math.cos(p) * a * TWO_OVER_SQRT_2, cy + Math.sin(p) * a * TWO_OVER_SQRT_2, a, p + TWO_PI * 5 / 8, p + TWO_PI * 3 / 8, true);
        ctx.closePath();
        ctx.stroke();
    }

    function rain(ctx, t, cx, cy, cw, s, color) {
        t /= 1350;

        var a = cw * 0.16,
            b = TWO_PI * 11 / 12,
            c = TWO_PI *  7 / 12,
            i, p, x, y;

        ctx.fillStyle = color;

        for(i = 4; i--; ) {
            p = (t + i / 4) % 1;
            x = cx + ((i - 1.5) / 1.5) * (i === 1 || i === 2 ? -1 : 1) * a;
            y = cy + p * p * cw;
            ctx.beginPath();
            ctx.moveTo(x, y - s * 1.5);
            ctx.arc(x, y, s * 0.75, b, c, false);
            ctx.fill();
        }
    }

    function sleet(ctx, t, cx, cy, cw, s, color) {
        t /= 750;

        var a = cw * 0.1875,
            b = TWO_PI * 11 / 12,
            c = TWO_PI *  7 / 12,
            i, p, x, y;

        ctx.strokeStyle = color;
        ctx.lineWidth = s * 0.5;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        for(i = 4; i--; ) {
            p = (t + i / 4) % 1;
            x = Math.floor(cx + ((i - 1.5) / 1.5) * (i === 1 || i === 2 ? -1 : 1) * a) + 0.5;
            y = cy + p * cw;
            line(ctx, x, y - s * 1.5, x, y + s * 1.5);
        }
    }

    function snow(ctx, t, cx, cy, cw, s, color) {
        t /= 3000;

        var a  = cw * 0.16,
            b  = s * 0.75,
            u  = t * TWO_PI * 0.7,
            ux = Math.cos(u) * b,
            uy = Math.sin(u) * b,
            v  = u + TWO_PI / 3,
            vx = Math.cos(v) * b,
            vy = Math.sin(v) * b,
            w  = u + TWO_PI * 2 / 3,
            wx = Math.cos(w) * b,
            wy = Math.sin(w) * b,
            i, p, x, y;

        ctx.strokeStyle = color;
        ctx.lineWidth = s * 0.5;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        for(i = 4; i--; ) {
            p = (t + i / 4) % 1;
            x = cx + Math.sin((p + i / 4) * TWO_PI) * a;
            y = cy + p * cw;

            line(ctx, x - ux, y - uy, x + ux, y + uy);
            line(ctx, x - vx, y - vy, x + vx, y + vy);
            line(ctx, x - wx, y - wy, x + wx, y + wy);
        }
    }

    function fogbank(ctx, t, cx, cy, cw, s, color) {
        t /= 30000;

        var a = cw * 0.21,
            b = cw * 0.06,
            c = cw * 0.21,
            d = cw * 0.28;

        ctx.fillStyle = color;
        puffs(ctx, t, cx, cy, a, b, c, d);

        ctx.globalCompositeOperation = 'destination-out';
        puffs(ctx, t, cx, cy, a, b, c - s, d - s);
        ctx.globalCompositeOperation = 'source-over';
    }

    /*
     var WIND_PATHS = [
     downsample(63, upsample(8, [
     -1.00, -0.28,
     -0.75, -0.18,
     -0.50,  0.12,
     -0.20,  0.12,
     -0.04, -0.04,
     -0.07, -0.18,
     -0.19, -0.18,
     -0.23, -0.05,
     -0.12,  0.11,
     0.02,  0.16,
     0.20,  0.15,
     0.50,  0.07,
     0.75,  0.18,
     1.00,  0.28
     ])),
     downsample(31, upsample(16, [
     -1.00, -0.10,
     -0.75,  0.00,
     -0.50,  0.10,
     -0.25,  0.14,
     0.00,  0.10,
     0.25,  0.00,
     0.50, -0.10,
     0.75, -0.14,
     1.00, -0.10
     ]))
     ];
     */

    var WIND_PATHS = [
            [
                -0.7500, -0.1800, -0.7219, -0.1527, -0.6971, -0.1225,
                -0.6739, -0.0910, -0.6516, -0.0588, -0.6298, -0.0262,
                -0.6083,  0.0065, -0.5868,  0.0396, -0.5643,  0.0731,
                -0.5372,  0.1041, -0.5033,  0.1259, -0.4662,  0.1406,
                -0.4275,  0.1493, -0.3881,  0.1530, -0.3487,  0.1526,
                -0.3095,  0.1488, -0.2708,  0.1421, -0.2319,  0.1342,
                -0.1943,  0.1217, -0.1600,  0.1025, -0.1290,  0.0785,
                -0.1012,  0.0509, -0.0764,  0.0206, -0.0547, -0.0120,
                -0.0378, -0.0472, -0.0324, -0.0857, -0.0389, -0.1241,
                -0.0546, -0.1599, -0.0814, -0.1876, -0.1193, -0.1964,
                -0.1582, -0.1935, -0.1931, -0.1769, -0.2157, -0.1453,
                -0.2290, -0.1085, -0.2327, -0.0697, -0.2240, -0.0317,
                -0.2064,  0.0033, -0.1853,  0.0362, -0.1613,  0.0672,
                -0.1350,  0.0961, -0.1051,  0.1213, -0.0706,  0.1397,
                -0.0332,  0.1512,  0.0053,  0.1580,  0.0442,  0.1624,
                0.0833,  0.1636,  0.1224,  0.1615,  0.1613,  0.1565,
                0.1999,  0.1500,  0.2378,  0.1402,  0.2749,  0.1279,
                0.3118,  0.1147,  0.3487,  0.1015,  0.3858,  0.0892,
                0.4236,  0.0787,  0.4621,  0.0715,  0.5012,  0.0702,
                0.5398,  0.0766,  0.5768,  0.0890,  0.6123,  0.1055,
                0.6466,  0.1244,  0.6805,  0.1440,  0.7147,  0.1630,
                0.7500,  0.1800
            ],
            [
                -0.7500,  0.0000, -0.7033,  0.0195, -0.6569,  0.0399,
                -0.6104,  0.0600, -0.5634,  0.0789, -0.5155,  0.0954,
                -0.4667,  0.1089, -0.4174,  0.1206, -0.3676,  0.1299,
                -0.3174,  0.1365, -0.2669,  0.1398, -0.2162,  0.1391,
                -0.1658,  0.1347, -0.1157,  0.1271, -0.0661,  0.1169,
                -0.0170,  0.1046,  0.0316,  0.0903,  0.0791,  0.0728,
                0.1259,  0.0534,  0.1723,  0.0331,  0.2188,  0.0129,
                0.2656, -0.0064,  0.3122, -0.0263,  0.3586, -0.0466,
                0.4052, -0.0665,  0.4525, -0.0847,  0.5007, -0.1002,
                0.5497, -0.1130,  0.5991, -0.1240,  0.6491, -0.1325,
                0.6994, -0.1380,  0.7500, -0.1400
            ]
        ],
        WIND_OFFSETS = [
            {start: 0.36, end: 0.11},
            {start: 0.56, end: 0.16}
        ];

    function leaf(ctx, t, x, y, cw, s, color) {
        var a = cw / 8,
            b = a / 3,
            c = 2 * b,
            d = (t % 1) * TWO_PI,
            e = Math.cos(d),
            f = Math.sin(d);

        ctx.fillStyle = color;
        ctx.strokeStyle = color;
        ctx.lineWidth = s;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        ctx.beginPath();
        ctx.arc(x        , y        , a, d          , d + Math.PI, false);
        ctx.arc(x - b * e, y - b * f, c, d + Math.PI, d          , false);
        ctx.arc(x + c * e, y + c * f, b, d + Math.PI, d          , true );
        ctx.globalCompositeOperation = 'destination-out';
        ctx.fill();
        ctx.globalCompositeOperation = 'source-over';
        ctx.stroke();
    }

    function swoosh(ctx, t, cx, cy, cw, s, index, total, color) {
        t /= 2500;

        var path = WIND_PATHS[index],
            a = (t + index - WIND_OFFSETS[index].start) % total,
            c = (t + index - WIND_OFFSETS[index].end  ) % total,
            e = (t + index                            ) % total,
            b, d, f, i;

        ctx.strokeStyle = color;
        ctx.lineWidth = s;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        if(a < 1) {
            ctx.beginPath();

            a *= path.length / 2 - 1;
            b  = Math.floor(a);
            a -= b;
            b *= 2;
            b += 2;

            ctx.moveTo(
                cx + (path[b - 2] * (1 - a) + path[b    ] * a) * cw,
                cy + (path[b - 1] * (1 - a) + path[b + 1] * a) * cw
            );

            if(c < 1) {
                c *= path.length / 2 - 1;
                d  = Math.floor(c);
                c -= d;
                d *= 2;
                d += 2;

                for(i = b; i !== d; i += 2)
                    ctx.lineTo(cx + path[i] * cw, cy + path[i + 1] * cw);

                ctx.lineTo(
                    cx + (path[d - 2] * (1 - c) + path[d    ] * c) * cw,
                    cy + (path[d - 1] * (1 - c) + path[d + 1] * c) * cw
                );
            }

            else
                for(i = b; i !== path.length; i += 2)
                    ctx.lineTo(cx + path[i] * cw, cy + path[i + 1] * cw);

            ctx.stroke();
        }

        else if(c < 1) {
            ctx.beginPath();

            c *= path.length / 2 - 1;
            d  = Math.floor(c);
            c -= d;
            d *= 2;
            d += 2;

            ctx.moveTo(cx + path[0] * cw, cy + path[1] * cw);

            for(i = 2; i !== d; i += 2)
                ctx.lineTo(cx + path[i] * cw, cy + path[i + 1] * cw);

            ctx.lineTo(
                cx + (path[d - 2] * (1 - c) + path[d    ] * c) * cw,
                cy + (path[d - 1] * (1 - c) + path[d + 1] * c) * cw
            );

            ctx.stroke();
        }

        if(e < 1) {
            e *= path.length / 2 - 1;
            f  = Math.floor(e);
            e -= f;
            f *= 2;
            f += 2;

            leaf(
                ctx,
                t,
                cx + (path[f - 2] * (1 - e) + path[f    ] * e) * cw,
                cy + (path[f - 1] * (1 - e) + path[f + 1] * e) * cw,
                cw,
                s,
                color
            );
        }
    }

    var Skycons = function(opts) {
        this.list        = [];
        this.interval    = null;
        STROKE       = opts && opts.stroke ? opts.stroke : 0.06;

        this.color = new Array();
        this.color["default"]  = opts && opts.color ? opts.color : "black";
        this.color["sun"] = opts && opts.sunColor ? opts.sunColor : this.color["default"] ;
        this.color["moon"] = opts && opts.moonColor ? opts.moonColor : this.color["default"] ;
        this.color["cloud"] = opts && opts.cloudColor ? opts.cloudColor : this.color["default"] ;
        this.color["rain"] = opts && opts.rainColor ? opts.rainColor : this.color["default"] ;
        this.color["snow"] = opts && opts.snowColor ? opts.snowColor : this.color["default"] ;
        this.color["wind"] = opts && opts.windColor ? opts.windColor : this.color["default"] ;
        this.color["fog"] = opts && opts.fogColor ? opts.fogColor : this.color["default"] ;

        this.resizeClear = !!(opts && opts.resizeClear);
    };

    Skycons.CLEAR_DAY = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        sun(ctx, t, w * 0.5, h * 0.5, s, s * STROKE, color["sun"]);
    };

    Skycons.CLEAR_NIGHT = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        moon(ctx, t, w * 0.5, h * 0.5, s, s * STROKE, color["moon"]);
    };

    Skycons.PARTLY_CLOUDY_DAY = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        sun(ctx, t, w * 0.625, h * 0.375, s * 0.75, s * STROKE, color["sun"]);
        cloud(ctx, t, w * 0.375, h * 0.625, s * 0.75, s * STROKE, color["cloud"]);
    };

    Skycons.PARTLY_CLOUDY_NIGHT = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        moon(ctx, t, w * 0.667, h * 0.375, s * 0.75, s * STROKE, color["moon"]);
        cloud(ctx, t, w * 0.375, h * 0.625, s * 0.75, s * STROKE, color["cloud"]);
    };

    Skycons.CLOUDY = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        cloud(ctx, t, w * 0.5, h * 0.5, s, s * STROKE, color["cloud"]);
    };

    Skycons.RAIN = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        rain(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["rain"]);
        cloud(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["cloud"]);
    };

    Skycons.SLEET = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        sleet(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["rain"]);
        cloud(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["cloud"]);
    };

    Skycons.SNOW = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        snow(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["snow"]);
        cloud(ctx, t, w * 0.5, h * 0.37, s * 0.9, s * STROKE, color["cloud"]);
    };

    Skycons.WIND = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h);

        swoosh(ctx, t, w * 0.5, h * 0.5, s, s * STROKE, 0, 2, color["wind"]);
        swoosh(ctx, t, w * 0.5, h * 0.5, s, s * STROKE, 1, 2, color["wind"]);
    };

    Skycons.FOG = function(ctx, t, color) {
        var w = ctx.canvas.width,
            h = ctx.canvas.height,
            s = Math.min(w, h),
            k = s * STROKE;

        fogbank(ctx, t, w * 0.5, h * 0.32, s * 0.75, k, color["cloud"]);

        t /= 5000;

        var a = Math.cos((t       ) * TWO_PI) * s * 0.02,
            b = Math.cos((t + 0.25) * TWO_PI) * s * 0.02,
            c = Math.cos((t + 0.50) * TWO_PI) * s * 0.02,
            d = Math.cos((t + 0.75) * TWO_PI) * s * 0.02,
            n = h * 0.936,
            e = Math.floor(n - k * 0.5) + 0.5,
            f = Math.floor(n - k * 2.5) + 0.5;

        ctx.strokeStyle = color["fog"];
        ctx.lineWidth = k;
        ctx.lineCap = "round";
        ctx.lineJoin = "round";

        line(ctx, a + w * 0.2 + k * 0.5, e, b + w * 0.8 - k * 0.5, e);
        line(ctx, c + w * 0.2 + k * 0.5, f, d + w * 0.8 - k * 0.5, f);
    };

    Skycons.prototype = {
        add: function(el, draw) {
            var obj;

            if(typeof el === "string")
                el = document.getElementById(el);

            // Does nothing if canvas name doesn't exists
            if(el === null)
                return;

            if(typeof draw === "string") {
                draw = draw.toUpperCase().replace(/-/g, "_");
                draw = Skycons.hasOwnProperty(draw) ? Skycons[draw] : null;
            }

            // Does nothing if the draw function isn't actually a function
            if(typeof draw !== "function")
                return;

            obj = {
                element: el,
                context: el.getContext("2d"),
                drawing: draw
            };

            this.list.push(obj);
            this.draw(obj, KEYFRAME);
        },
        set: function(el, draw) {
            var i;

            if(typeof el === "string")
                el = document.getElementById(el);

            for(i = this.list.length; i--; )
                if(this.list[i].element === el) {
                    this.list[i].drawing = draw;
                    this.draw(this.list[i], KEYFRAME);
                    return;
                }

            this.add(el, draw);
        },
        remove: function(el) {
            var i;

            if(typeof el === "string")
                el = document.getElementById(el);

            for(i = this.list.length; i--; )
                if(this.list[i].element === el) {
                    this.list.splice(i, 1);
                    return;
                }
        },
        draw: function(obj, time) {
            var canvas = obj.context.canvas;

            if(this.resizeClear)
                canvas.width = canvas.width;

            else
                obj.context.clearRect(0, 0, canvas.width, canvas.height);

            obj.drawing(obj.context, time, this.color);
        },
        play: function() {
            var self = this;

            this.pause();
            this.interval = requestInterval(function() {
                var now = Date.now(),
                    i;

                for(i = self.list.length; i--; )
                    self.draw(self.list[i], now);
            }, 1000 / 60);
        },
        pause: function() {
            var i;

            if(this.interval) {
                cancelInterval(this.interval);
                this.interval = null;
            }
        }
    };

    global.Skycons = Skycons;
}(this));
